1. Field of the Invention
The present invention relates to a method of finishing pile fabrics and an apparatus therefor. The present invention relates more particularly to a method of inclining piles of plush ribbon used as light-trapping members to be attached to a film passage mouth of a photographic film cassette, especially for those where a film leader is advanced out of the photographic film cassette through the film passage mouth.
2. Related Art
It is well known in the art of photographic film cassette to attach light-trapping members made of plush ribbon to the upper and lower inside surface of the film passage mouth, in order to shield ambient light from interior of the cassette.
Recently, photographic film cassettes, in which an entire photographic film is wound on a spool and contained in a cassette shell in order to facilitate the loading of the photographic film cassette into a camera, have been suggested. In such a photographic film cassette, the leading end of the photographic film is advanced out of the cassette shell, through a film passage mouth, by rotating the spool in a film advancing direction or film unwinding direction.
For these leader-advancing type photographic film cassettes, it is necessary to incline piles of the plush ribbon in the width direction of the light-trapping members toward the film advancing direction, in order to reduce advancing torque of the spool or resistance against the film advance through the light-trapping members.
A method of making such a light-trapping member that has inclined piles is disclosed in U.S. application Ser. No. 08/050,567 (filed on Apr. 21, 1993, corresponding to Japanese Patent Application No. 4-101152), wherein the piles of the plush ribbon are pressed against the peripheral surface of a heating drum, while the ribbon being fed in the longitudinal direction and twisted relative to the ribbon feeding direction.
It is also disclosed in the prior art to impart inclination to the piles of the plush ribbon in the longitudinal direction by rotating the heating drum at a different peripheral speed from the feeding speed of the plush ribbon. The inclination of the piles in both width and longitudinal directions, that is, in a diagonal direction, contributes to smooth and unfailing film advance. This is because the piles of the one light-trapping member can be oriented in a diagonal direction crossing the piles of the other light-trapping member, so that the piles are prevented from getting tangled.
However, in the above-mentioned pile inclining method, the force that makes the piles incline in the width direction is applied to the piles merely in a moment when the plush ribbon contacts the heating drum. Therefore, the force is insufficient for the inclination in the width direction, so that it is difficult to permanently incline the piles of the plush ribbon in a diagonal direction by the above-described method.